Campylobacter is a major human enteric pathogen. Although breastfeeding protects infants against diarrheal disease, information regarding the role of breast milk in preventing diarrhea due to campylobacter is incomplete. The specific aims of this project are to: 1) characterize antibodies in breast milk against specific campylobacter virulence factors (adherence factors and enterotoxin); 2) evaluate milk for non-antibody factors that might interfere with adherence, invasion and toxin action; 3) determine the frequency of symptomatic and asymptomatic campylobacter infection in breastfed and non- breastfed infants; 4) determine the association of specific antibodies and cell receptor analogs in breast milk with asymptomatic and symptomatic infection; and 5) determine the effect of breastfeeding on the specific virulence antigen related fecal sIgA and serum immune responses which develop during asymptomatic and symptomatic camyplobacter infection. The present proposal will allow us to better understand the role of breast milk in campylobacter infection in childhood and to delineate the mechanisms by which milk interacts with this enteropathogen. In addition, breast milk immune responses may reflect the mechanisms of protection that occur in the intestine and better define the immune response to the virulence elements.